Electrokinetic remediation is an emerging technology for the remediation of organic contaminated soil. In the existing electrokinetic remediation process, electrodes are inserted into contaminated soil to form an electrode matrix, and a weak direct current is applied to form an electric field. Under the combined action of electrochemical reactions and electrokinetic effects, organic pollutants in soil can be effectively removed.
The present study indicates that the degradation of organic pollutants is mainly implemented through electrochemical oxidation, and the degradation rate of pollutants is in positive correlation with the electric field intensity. Such degradation of organic pollutants by the field intensity mainly occurs around electrodes, especially an acid soil region caused by anode reaction. This is because an electrode composed of good conductors is an electronic conductor, and electrode reaction occurs to the soil around same, thereby promoting the execution of electrochemical reactions and efficiently degrading organic pollutants. However, soil is an ion conductor. Therefore, in the soil away from the electrode, the field intensity is relatively weak, and the degradation efficiency of organic pollutants is relatively low.
At the present stage, to reduce the space of the degradation rate of organic pollutants, a manner of forming an electric field with relatively uniform field intensity through electrode arrangement and electrode polarity switching is used (CN 102294350 B). However, because the concentrations of organic pollutants in soil are non-uniformly distributed, it is difficult for the field intensity to match a pollutant concentration field. Aiming at this problem, the frequently-used methods for field intensity compensation include: first, the spatial distribution of field intensity is controlled by changing the electrode potential around a region of field intensity to be compensed from the potential; second, local field intensity is adjusted by changing the electrode density of the region of field intensity to be compensated from the electrode density; and third, the two are combined.
However, because these methods all need to use an external power supply, energy consumption and maintenance costs are increased, and moreover, such important current situation, i.e. the gradient change of the potential of the existing electric field in space is neglected. Therefore, how to use the change in the difference of potential in the electric field to enhance local field intensity in an arrangement manner of paired diversion electrodes, construct the spatial distribution of the field intensity matching the pollutant concentration field, and strengthen the degradation of organic pollutants has important significance for increasing the overall efficiency of electrokinetic remediation for organic contaminated soil.